I have an internal web server who's address is:
http://'servername':8080/dashboard.action

I want to set up its internal DNS to be:
confluence.'domainname'.net

I created an A record that reflects this information however when I go to confluence.'domainname'.net I get the tomcat root page not the actual content of the host address.

what do I need to do in DNS to correct this?

Nothing - this is not a DNS issue. The problem is you have another web server listening on port 80. Correct me if I'm wrong, but you are NOT using IIS, right? So you would probably be better off asking this in a forum for the web server that you ARE using.

Correct, we're running Tomcat, not IIS. Tomcat is listening on port 80 for other uses but I need to somehow get http://'servername':8080/dashboard.action to resolve to confluence.'domainname'.net

if this is not a DNS issue, can you tell me where I need to make the necessary configuration changes?

I'm not familiar with tomcat, so, as I said, you are better off asking this in a forum for the web server that you ARE using.

DNS just locates the server, not the services on it. You've found the server because you are getting a response. Now you have to configure TomCat to respond differently to different domains. In IIS, this would be configuring host header information... in Apache... it's different... and I have no idea on TomCat - but it's not DNS.